[A case of transient parkinsonism due to mesencephalic hemorrhage].

A 68-year-old man was admitted because of sudden onset gait disturbance and bradykinesia. He experienced left putaminal bleeding following mild right hemiparesis and emotional incontinence without any difficulties in his daily life since three years before admission. On neurological examination the patient was alert and oriented. He showed forced crying. Myerson's sign was positive. There were no abnormal findings in ocular movements, pupillary reflexes and other cranial nerves. Muscle tone was increased with cog-wheel phenomenon in bilateral upper extremities. Coordination was preserved. He showed severe akinesia and small steppage gait with stooped posture. Freezing phenomenon was observed in initiation of gait and turning. The deep tendon reflexes were increased in the right side with bilateral pathological reflexes. There was no definite weakness and sensory disturbance in all extremities. Brain CT revealed a small high density lesion in the medial side of right cerebral peduncle and a lens-shaped low density lesion in the left putamen. On T1 and T2 weighted images of MRI, right peduncular lesion showed low signal. It extended to the substantia nigra which was partially destructed. His parkinsonism was rapidly improved and completely disappeared within following two weeks. High density lesion of right peduncle on CT also disappeared. We discussed the mechanisms of parkinsonism following unilateral mesencephalic hemorrhage in this patient.